CLIMATES OF THE OCEAN. 295 



tionary there, and then liken the tail of the Stream itself to an im- 

 mense pennon floating gently in the current, such a motion as such 

 a streamer may be imagined to have — very much such a motion — 

 do my researches show the tail of the Gulf Stream to have. Run- 

 ning between banks of cold water (§ 1), it is pressed now from the 

 north, now from the south, according as the great masses of sea 

 water on either hand may change or fluctuate in temperature. 



849. In September, when the waters in the cold regions of the 

 north have been tempered, and made warm and light by the heat 

 of summer, its limits on the left (Plate VI.) are as denoted by the 

 line of arrows ; but after this great sun-swing, the waters on the 

 left side begin to lose their heat, grow cold, become heavy, and 

 press the hot waters of this stream into the channel marked out 

 for them. 



850. Thus it acts like a pendulum, slowly propelled by heat on 

 one side and repelled by cold on the other. In this view, it be- 

 comes a chronograph for the sea, keeping time for its inhabitants, 

 and marking the seasons for the great whales ; and there it has 

 been for all time vibrating to and fro, once every year, swinging 

 from north to south, and from south to north again, a great self- 

 regulating, self-compensating pendulum. 



851. In seeking information concerning the climates of the 

 ocean, it is well not to forget this remarkable contrast between its 

 climatology and that of the land, namely : on the land, February 

 and August are considered the coldest and the hottest months ; 

 but to the inhabitants of the sea, the annual extremes of cold and 

 heat occur in the months of March and September. On the dry 

 land, after the winter " is past and gone," the- solid parts of the 

 earth continue to receive from the sun more heat in the day than 

 they radiate at night, consequently there is an accumulation of 

 caloric, which continues to increase until August. The summer 

 is now at its height ; for, with the close of this month, the solid 

 parts of the earth's crust and the atmosphere above begin to dis- 

 pense with their heat faster than the rays of the sun can impart 

 fresh supplies, and, consequently, the climates which they regu- 

 late grow cooler and cooler until the dead of winter again. 



852. But at sea a different rule seems to prevail. Its waters 



